Method of coating containers



Feb. 8,` 1938. J. LIT-HGow 2,108,017-

METHOD OF COTING CONTAINERS Feb. 8, 1938. J. LlTHGow 2,108,017

METHOD 0F COATING CONTAINERS Filed Feb. 27, 1956 2 Sheets-Sheerl 2Patented Feb. 8, 1938 UNI-TED STATES PATlezrrr OFFICE METHOD OF COA'IINGCONTAINERS James Lithgow, Chicago, Ill., assignor to LithgowCorporation, Chicago, Ill., a corporation of Del- Application February27, 1936, Serial No. 65,978

y6 Claims.

large tanks such as tank cars, and tanks mounted in position forpermanent installation as in breweries, factories, or the like.

Heretofore several methods have been used or proposed for lining suchtanks or containers. One of these methods contemplates the use of glassor vitreous enamel which can only be applied at the factory where thecontainer is made and requires high temperatures or around 1700Fahrenheit to apply the same. Another method consists in the relativelycold application o f pitch or base coatings in which small sections ofthe surface of the container are treated at a time. Another method'contemplates spraying nonferrous metals on the inner surface but all ofthese different processes have been found objectionable for variousreasons which are familiar to those having to do with this art.

In accordance with the present invention I provide a novel method ofcoating or lining containers of the character indicated wherebythecontents such as various foods, drinks, or bulk liquids may bemaintained in a sterile condition and will be protected fromcontamination or discoloration through contact with the material of thecontainer. My improved process involves the use of a suitable liningmaterial such as low temperature baking enamel or lacquer which isinert, when properly cured or baked, to food products or other contentsto be placed or kept in the container. There are a large variety oftypes or kinds of paints, enamels or lacquers which are adapted to beused for the present purposes to meet the particular conditions asrespect to the food or materials to be placed in the container and thepresent invention contemplates the use of any suitable coating materialwhich may be adapted for the particular use for which the tank orcontainer is intended.

l The principal object of the present invention is to provide a methodof lining or coating containers, tanks, or the like, particularly afterthe r same have been mounted or installed in operatparticularly from thefollowing description taken in connection with the accompanying drawingsin which l Figure 1 is a longitudinal sectional view of a tankcar'illustrating an application of my im proved method;

Figure 2 is a cross sectional view of the same showing the heatingapparatus;

Figure 3 is a longitudinal sectional view illustrating any ordinary orpreferred form of processing tank which is being lined or coated; l0

ceiving the coating or lining l on material which is capable of beinghardened by baking at a relatively low temperature, such as paint,enamel or lacquer which may be applied in any suitable manner butpreferably by means of a brush. This coating will ordinarily be allowedto air dry for about three hours or-more and is then baked on inaccordance with my improved system` Any `number of coats may then beapplied and baked on in accordance with the followingmethody but it willonly be necessary to describe the operation for the first coat.

The tank which will ordinarily be made of steel or similar metal isenclosed or coveredwith a sectional insulating blanket 8 of any suitable35 material such as mineral wool, 0r other material which will lenditself to being formed into portable sections so that they may betransferred from tank to tank and connected together in any suitablemanner or fastened onto the outer surface of the tank to suit the4various sizes and shapes thereof.

It is necessary or desirable to be able to determine .the temperature ofthe metal of all parts of the tank or container which is being treated4- which may be done by any suitable temperature measuring apparatussuch as thermometers, pyrometers, or the like. As a convenient method ofdetermining the temperatures at dierent parts of the tank I providewires or thermo-couples such as shown at 9 which are suitably connectedwith the tank and which may lead to the measuring instrument such as aportable potentiometer, thermostat, pyrometer or the like. These wiresare preferably arranged so that the difdisconnected with'the instrumentso that any desired number of temperature reading may be made for thedifferent portions of the container. It is necessary to determine thetemperature of the metal of the container as the bonding of the coatingto the inner surface of the metal is quite critical as respects to thetemperature. If the temperature is too low the lacquer or coating willnot be properly cured and baked and if the temperature becomes too highthe coating is apt to become brittle. It is necessary to take thetemperatures of the metal at various points throughout the tank orcontainer in order to have all parts thereof heated to the properdegree. This will be more readily understood when it is 4considered thattank cars which I have treated in accordance with this method areapproximately seven feet in diameter and thirtytwo to thirty-eight feetlong. Storage or other tanks which I have lined in accordance with thisprocess have been upwards of twelve feet in diameter and seventy feetlo'ng. The tendency of heat is to rise and accordingly it is necessaryto provide means for properly determining the temperature at differentportions of the tank and particularly along the bottom in order toinsure proper curing and baking of the coating throughout the interiorsurface.

The heat for baking may be derived from any suitable source but I haveshown a portable furnace or heater Il which may be heated by thecombustion of gas, oil, solid fuel, or the like. The furnace is directlyconnected to a fan I2 which is driven by a motor I3 which may be of thevariable type in order to regulate the air supply. A conduit or pipe I4leads from the'furnace into the tank or container 6 where it is providedwith discharge means for equalizing the distribution of the hot airthroughout the container. As shown in Figure 1 the pipe I4 has twolateral discharge branches I5 directed toward the ends of the tank and adown discharge branch I6 directed toward the bottom and outlet I1 of thetank. 'Ihese outlets are preferably provided with screens I8 to preventany objectionable particles being blown into the container. After theheating apparatus has been arranged as shownv the curing and baking areaccomplished by blowing a sumcient volume of hot air or gas into thetank to reach all interior surfaces and to raise the temperature to anydesired degree. For instance with some lacquers the temperature isgradually raised forthree or four hours; until the temperature of themetal of the container reaches approximately 250 F. to 275 F. ,andthevtemperature is held at this point for. about one hour.

Of course the time and amout of heat will be dependent upon thecharacter of the coating material as above suggested. The hot air orgases forced into the container from the furnace I I are permitted toescape through any suitable openings in the container and as shown inFigure 1 the outlet pipe or connection I1 which is also lined or coatedwill serve as an escape and at the same time will become sufficientlyheated to bake the lacquer applied therein. The distribution of the airthroughout the tank may also be con. trolled by arranging the outletopenings in order to suit the type or shape of the tank. After thedesired number of coatings have been applied the heating equipment maybe removed and the tank will be in condition for use. The sectional orremovable insulation 8 and the portable heating ferent pairs may beconveniently connected and apparatus may be readily moved from one tankto another as will be readily understood.

The tank I9 shown in Figure 3 may represent a horizontal type ofcontainer intended for industrial purposeswhich is shown with a coating20. The inlet pipe 2| for conducting heat from the furnace or source ofheat supply is preferably stepped ldown or reduced in diameter toprovide sections 22 and 23 and this discharge portion is provided withholes 24 which are arranged along the same as indicated in order todirect the heat or hot air to the different portions of the tank. Thepipe 2| may be supported in the tank by means of hangers or supports 25or in any other suitable manner. In this arrangement the tank is alsoprovided with temperature measuring means or thermo-couples the same asin the form shown in Figure 1.

The upright tank 26 shown in Figure 4 is provided with a lacquer lining21 which is applied as above described. In this instance the inlet pipe28 has a vertical branch 29 with holes 30 in the sides thereof. 'I'heupper end of the branch 29 may be provided with a deilector 3| and ahole or opening left in the lower end, the entire arrangement being suchthat the heat will be spread uniformly throughout the tank in order togive an even or uniform baking of the coating throughout the tank.

Figure 5 shows a tank 32 having an upper portion made of wood and abottom or base 33 formed of metal such as cast iron, which type of tankis in more or less common use. While it is not necessary to coat themain part of the tank it is desirable to coat or line the bottom 33 witha lining 34 as shown. The heat is introduced as above described througha pipe 35 from any suitable source of heat supply, this pipe beingconveniently introduced at the ,bottom and provided at its upper endwith a deilector 36 for distributing the gases which escape throughopenings 31. In order to conne the lining to the cast iron or metalbottom I provide a floor or partition 38 which is arranged above theupper end of the bottom and which has a lower insulating surface 39 forretaining the heat. This partition is preferably made in sections foreasy insertion and so that it may be used for different tanks ifdesired.

The application of the heat to these different forms of tanks will beapparent from the above description. 'I'he amount of heat and regulationthereof may be controlled in any well known manner as by regulating theamount of fuel supplied to the furnace or heater and by varying thespeed of the fan motor and the heat supplied to diierent portions of thetank may be .regulated by moving the inlet pipes or changing the outletopenings. After the one or several layers of lacquer or coating havebeen applied and baked on, the heat conducting and distributing devicesand the temperature measuring apparatus and other parts may be removedand the tank or container will be ready for use.

In the actual application of this invention for commercial purposes Ihave found that by using a lacquer which can be applied at roomtemperatures a perfect bond will be made withv the steel and an evencoat provided over all surfaces. My

improved method of baking provides full temper l tively low temperaturesI am able to bake vessels 7s of irregular shape without distortion andcan also operate on tanks in places such as brewery cellars which mustbe maintained at temperatures not over 40 F. without interfering withthe regular plant operation. 'I'his process also provides means forrecoating or lining old tanks which would otherwise have to be replacedat great expense and with resulting loss of operation while the tankswere transferred and which might also require the demolition of buildingwalls to permit exit and entry of the tanks. The use of my method forlining the bottom cones or bases of wooden tanks is also highlydesirable as it may be done without injury to the wooden staves and thislls a long felt Want of several chemical industries in which productsare handled which affect metal but which nevertheless require the use ofmetal bottoms in order to make the necessary pipe connections.

While l have outlined various uses and advantages of my invention it mayalso be applicable to other containers and other advantages may beapparent to those familiar with the art. Any invention or subject matterherein shown and described but not claimed, is not intended to bededicated to the public, insofar. as such subject matter is shown,described and claimed in my copending application for Metal coating,illed December 2, 1937, Serial No. 177,781. Accordingly I do not wish tolimit my claims to the particular method or apparatus herein shown ordescribed except as specified in the following claims in which I claim.

1. The method of lining a metal tank which comprises rst covering thetank with a covering of heat insulating material, then coating the innersurface of the tank with a suitable coating material which is adapted tobe baked on, permitting said coating material to air dry, thenintroducing a conduit into the tank and forcing gases heated to thenecessary temperature for baking the coating material, after it hasbecome dry, through the conduit into the tank for a sufficient length oftime to bake the coating to a uniform hardness, said gases beingpermitted to escape from the tank as the baking progresses.

2. 'Ihe process of coating relatively large metal tanks mounted inposition for permanent insullation, which comprises applying a lining ofa materialwhich is capable ofbeing" baked at a relatively lowtemperature to harden the same, then providing a portable furnace havinga pipe adapted to lead therefrom into the container and having means forblowing air therethrough, then driving the heated air through said pipeinto the container for a sulcient length of time to bake the liningapplied thereto to obtain a lining of uniform hardness.

3. The process of coating the interiors of relatively large metal tanksmounted in position for permanent installation, which includes placing ay 4. The method of coating the metal portion of a tank, which comprisesclosing off said metal portion from the remainder of the tank, thenpainting the inner surface of said portion with a material which iscapable of being hardened by baking at av relatively low temperature,temporarily covering the exposed outer surfaces of said portion withinsulating material to be kept thereon during the baking process only,then directing gases which are heated to a baking temperature into saidportion, said gases being directed into said portion a suflicient lengthof time to bake said material to a uniform hardness, and finallyremoving the insulation from said portion.

5. The herein described method of applying durable and substantiallypermanent linings to large metal tanks, metal tank cars, or the like,which comprises covering the tank temporarily with insulating materialto prevent loss of heat during the baking operation, then coating theinner surface of the tankwith a suitable lining material which iscapable of being hardened by baking at a relatively low temperature,allowing said lining to dry, then directing into the tank, gases whichare heated sumciently to harden the lining material, and nally removingthe insulating material, leaving said tank with a suitably hardenedlining as Aandfor the purposes described.

6. The herein described method of protecting the interiors of metalcontainers of large size from the action of material placed therein,which comprises covering the container with a heat insulating cover,cleaning the inner surfaces of the container by sand-blasting, thenapplying a layer of coating material in liquid form, which material isof a nature that it may be hardened to the desired consistency bybaking, allowing the layer to air dry until thoroughly dried, thenforcing heated gases under pressure into the container. and graduallyraising the temperature of the metal ofi-the container until it reachesapproximately 250 F. to 275 F. and holdingthe 55 temperature atapproximately this heat until the layer is suiliciently hardened, thenpermitting the tank to cool, and removing the insulation from the outersurface thereof.

- JAMES LITHGOW.

